Radiative thermoregulation can reduce the energy consumption for heating, ventilation and air-conditioning (HVAC) in buildings, and therefore contribute substantially to climate change mitigation. Electrochromism, a phenomenon in which a material exhibits reversible colour changes under an external electrical stimulus, can help control the heat balance of buildings in response to fluctuating weather conditions; however, its implementation has been largely limited to visible and near-infrared wavelength regimes. Here we develop an aqueous flexible electrochromic design for use as a building envelop based on graphene ultra-wideband transparent conductive electrode and reversible copper electrodeposition, in which the thermal emissivity can be tailored to vary between 0.07 and 0.92 with excellent long-term durability. Building energy simulations show that our design as building envelopes can save on year-round operational HVAC energy consumption across the United States by up to 43.1 MBtu on average in specific zones. Such dynamic emissivity tunability can further serve as a non-destructive technological solution to retrofit poorly insulated or historic buildings. Our work suggests a feasible pathway to radiative thermoregulation for more energy-efficient HVAC and solving some of the global climate change issues.
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All data needed to support the conclusions in the paper are present in the manuscript and/or Supplementary Information. Additional data related to this paper may be requested from the corresponding authors.
Codes for DFT simulation are available on GitHub at https://github.com/kianpu34593/asebasic. Custom codes in Matlab and Python used for EMT calculation, building energy saving simulation and postprocessing are available upon written request from the corresponding authors.
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We thank M. D. McGehee and A. L. Yeang (University of Colorado, Boulder, Department of Chemical and Biological Engineering) for the valuable discussion regarding electrodeposition and electrolyte synthesis, G. Tan (Zhejiang University) for kindly helping with the building energy saving calculation, and D. Wang (University of Chicago, Department of Chemistry) for helping with EDX mapping. The project was sponsored by the Collaboration Grants for Climate Change from Nicholas Institute for Energy, Environment & Sustainability and the startup fund by Pratt School of Engineering at Duke University.
P.-C.H., C.S. and Y.R. have a 2021 US patent application (63/256,136). The other authors declare no competing interests.
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Sui, C., Pu, J., Chen, TH. et al. Dynamic electrochromism for all-season radiative thermoregulation. Nat Sustain (2023). https://doi.org/10.1038/s41893-022-01023-2